The scraps probably aren't all that necessary. The only real trick is making sure that you get the stencil taped onto the blade straight. If you want a deep etch, don't leave the wand on the blade for a long time. Do multiple etches of like 10-20 seconds. Just let it etch and then remove for a few seconds and do the next one. That in theory will make your stencils last longer. When you pull the wand away, you should see the etching liquid "fizzing" a little bit. if it doesn't, that means that you don't have a connection. I did that once and realize that I had forgotten to clamp the other lead to the blade. LOL. I put my blades in a Moran vise and clip the alligator clip to the tang so that there is no chance of any of the polished part of the blade getting marred or discolored.